Layered magnesium aluminosilicates can be described as a type of clay comprising alternating layers of octahedrally co-ordinated magnesium atoms and tetrahedrally co-ordinated silicon and/or aluminum atoms. Magnesium aluminosilicate clays have a negative layer charge which can be balanced by cations. Among other characteristics, the type of charge balancing cations imparts catalytic activity to the magnesium aluminosilicate clays. The literature contains examples of magnesium aluminosilicate clays, methods of making magnesium aluminosilicate clays, and catalyst compositions comprising magnesium aluminosilicate clays.
The literature describes the synthesis of clay minerals under hydrothermal conditions. Such hydrothermal synthesis can involve a long hydrothermal treatment at relatively high temperatures and pressures. The application of this technology on an industrial scale can be difficult and costly due to the reaction conditions employed.
Other known methods for producing clay materials such as metallo-aluminosilicates involve the formation of a silica-alumina gel prior to addition of the metallo component. For a review of silica-alumina gel synthetic methods for preparing metallo-aluminosilicates and other clay materials see, for example, R J M J Vogels, J T Kloprogge, and J W Geus, Amer. Mineral. (2004), “Synthesis, characterization of saponite clays”, 931-944. Yields of products produced via a silica-alumina gel can be better than in the hydrothermal synthetic route, but are generally not quantitative. In addition, formation of a silica-alumina gel requires an added step in the synthesis of the clay material.
While synthesis of clays can be difficult, particularly on a large scale, clays have received attention for use in catalytic processes such as cracking or as catalyst components in hydroprocessing reactions. For example, U.S. Pat. No. 3,844,978 discloses a layer-type, dioctahedral, clay-like mineral useful in catalytic processes. U.S. Pat. No. 3,844,979 discloses a layer-type trioctahedral, clay-like mineral that is a magnesium aluminosilicate, catalyst composition comprising said magnesium aluminosilicate, and hydroprocesses for using said magnesium aluminosilicate.
U.S. Pat. No. 3,887,454 discloses hydroconversion processes using a layer-type, dioctahedral, clay-like mineral that is a magnesium aluminosilicate. Catalyst compositions and hydroprocessing reactions using catalyst compositions comprising magnesium aluminosilicates and hydrogenation components such as Group VIII metals are also disclosed.
U.S. Pat. No. 6,187,710 and U.S. Pat. No. 6,565,643 disclose synthetic swelling clay minerals, methods of making swelling clay minerals, and the use of said swelling clay minerals as hydrocarbon reaction catalysts. U.S. Pat. No. 6,334,947 discloses catalysts compositions comprising a swelling clay and the use of said catalyst compositions in hydroprocessing reactions. Magnesium aluminosilicates are examples of swelling clays disclosed in U.S. Pat. No. 6,187,710, U.S. Pat. No. 6,565,643, and U.S. Pat. No. 6,334,947.
There still exists a need for improved methods of synthesizing magnesium aluminosilicate clays and for magnesium aluminosilicate clays with improved characteristics that can be used as catalysts or components of catalyst compositions in hydroprocessing and other applications.